Ink jet printers include an ink jet modulator which projects charged ink droplets that are deflected to form an information pattern on a moving document. Examples of multi-orifice printers may be found in U.S. Pat. Nos. 3,373,437, 3,714,928 and 3,739,395. Ink modulators associated with ink printers normally have been electromechanically tuned at a particular drop rate. Any deviation in the operation from the resonant frequency has been accompanied by a deterioration in the modulator efficiency resulting in intolerable changes in the distance between the nozzle and the droplet break-off point. Variation in the distance of the break-off point from the nozzle affects the drop charging function which may result in poor quality printing. Prior modulator systems have been characterized by an acute sensitivity to temperature changes, and have a propensity for generating satellite droplets about the primary ink jet stream due to a shift in the resonant frequency of the crystal.
When the transport velocity changes, it is necessary to provide a corresponding change in the drop rate. Typical prior art ink jet printers operate at a single frequency and are used on equipment utilizing a single speed. Changes in drop rate to accommodate a change in transport speed has been reflected by a degradation of printing quality.
In the development of some multiple nozzle configurations, complex systems having plural transducer-diaphragm combinations have been required. U.S. Pat. No. 3,708,798 discloses a multi-nozzle printer having a plurality of piezoelectric transducers secured to a like plurality of diaphragms which pulsate the ink towards a set of nozzles. In U.S. Pat. No. 3,900,162 an ink gun comprised of a diamond-shaped ink chamber feeds multiple orifices to form droplets at approximately the same time and at a near uniform distance from the orifices. The diamond shaped chamber is divided along its diagonal by a vibrating member and has a plurality of transducers affixed to one side of the member.